Going to Wyoming...

Maybe not part of the route but obviously don't miss Yellowstone while you are there. Make a loop from your brother's into Teton, up into Yellowstone, around the park, then go up and out of the park in Cook City, over Dead Indian pass down into Cody, then back to your brother's. I drove Missoula Montana to St Louis a few years back and went through Yellowstone and over Dead Indian pass then diagonally across Wyoming and was much pleased even though that was not planned detour because of flooding in Montana.